Environmental induction of the fetal epigenome

Ambient air pollution and adverse birth outcomes: A review of underlying mechanisms

Epidemiological data provide varying degrees of evidence for associations between prenatal exposure to ambient air pollutants and adverse birth outcomes (suboptimal measures of fetal growth, preterm birth and stillbirth). To assess further certainty of effects, this review examines the experimental literature base to identify mechanisms by which air pollution (particulate matter, nitrogen dioxide and ozone) could cause adverse effects on the developing fetus. It likely that this environmental insult impacts multiple biological pathways important for sustaining a healthy pregnancy, depending upon the composition of the pollutant mixture and the exposure window owing to changes in physiologic maturity of the placenta, its circulations and the fetus as pregnancy ensues. The current body of evidence indicates that the placenta is a target tissue, impacted by a variety of critical processes including nitrosative/oxidative stress, inflammation, endocrine disruption, epigenetic changes, as well as vascular dysregulation of the maternal-fetal unit. All of the above can disturb placental function and, as a consequence, could contribute to compromised fetal growth as well increasing the risk of stillbirth. Furthermore, given that there is often an increased inflammatory response associated with preterm labour, inflammation is a plausible mechanism mediating the effects of air pollution on premature delivery. In the light of increased urbanisation and an ever-changing climate, both of which increase ambient air pollution and negatively affect vulnerable populations such as pregnant individuals, it is hoped that the collective evidence may contribute to decisions taken to strengthen air quality policies, reductions in exposure to air pollution and subsequent improvements in the health of those not yet born.

Pediatrics Consequences of Caesarean Section-A Systematic Review and Meta-Analysis

BACKGROUND

Cesarean section is a surgical procedure, which is the most frequently performed in gynecology and obstetrics. It is commonly believed that an operative delivery is a less painful and safer mode of delivery, which translates into an increasing number of the procedures performed without medical indications. The maternal sequelae of cesarean sections are well elucidated and widely discussed in the literature, while long-term neonatal consequences still remain the issue of research and scientific dispute. The aim of the present paper was to perform a systematic review of current literature regarding pediatrics consequences of cesarean section.

METHODS

We reviewed available data from PubMed, Science Direct as well as Google Scholar bases concerning early and long-term neonatal sequelae of operative deliveries. The following key words were used: "cesarean section", "caesarean section", "neonatal outcomes", "respiratory disorders", "asthma", "obesity", "overweight", and "neurological disorders". A total of 1636 papers were retrieved out of which 27 were selected for the final systematic review whereas 16 articles provided data for meta-analysis. Statistical analyses were performed using RevMan 5.4. To determine the strength of association between the caesarean section and respiratory tract infections, asthma, diabetes type 1 as well as obesity the pooled odds ratios (OR) with the 95% confidence intervals (CI) were calculated.

RESULTS

Conducted meta-analyses revealed that caesarean section is a risk factor for respiratory tract infections (pooled OR = 1.30 95%CI 1.06-1.60, p = 0.001), asthma (pooled OR = 1.23 95%CI 1.14-1.33, p < 0.00001) as well as obesity (pooled OR = 1.35 95%CI 1.29-1.41, p < 0.00001) in offspring.

CONCLUSIONS

The results of the studies included indicated that children delivered by cesarean section more commonly developed respiratory tract infections, obesity and the manifestations of asthma than children delivered vaginally. The risk of developing diabetes mellitus type 1 or neurological disorders in offspring after caesarean section is still under discussion.

Association of intrauterine exposure to aspirin and blood pressure at 7 years of age: a secondary analysis

OBJECTIVE

To examine whether maternal aspirin use during pregnancy is associated with childhood blood pressure.

DESIGN/SETTING

A secondary analysis of the Collaborative Perinatal Project, a prospective cohort study including 12 US academic medical centres between 1959 and 1976.

POPULATION

Singleton births among women with detailed medication information.

METHODS

We carried out linear and multivariate logistic regression analysis to assess the associations between maternal aspirin exposure and childhood blood pressure at age 7 years.

MAIN OUTCOME MEASURES

Offspring blood pressure at age 7 years.

RESULTS

A total of 15 793 women were exposed to aspirin 4 weeks before the last menstrual period or during pregnancy. In utero aspirin exposure may be associated with an 11% (95% CI 0.85- 0.93) and a 20% (95% CI 0.76-0.84) reduced risk of having high systolic blood pressure (SBP) and diastolic blood pressure (DBP) at 7 years of age, and a mean decrease of 0.62 mmHg for SBP and 1.04 mmHg for DBP at 7 years of age. Compared with children born to mothers without aspirin exposure, those whose mothers were exposed to aspirin for at least 7 days during pregnancy had approximately 10% and 27% reduced risk of high SBP and DBP, respectively, and a mean reduction of 0.61 and 1.27 mmHg in SBP and DBP at 7 years of age. The earlier the aspirin exposure occurred during pregnancy, the lower the risk of childhood high blood pressure.

CONCLUSION

In utero exposure to aspirin may have long-term benefits for childhood blood pressure.

TWEETABLE ABSTRACT

Maternal aspirin exposure might decrease the risk of childhood blood pressure.

Risk of Cancer in Children Conceived by Assisted Reproductive Technology

BACKGROUND AND OBJECTIVE

An increasing number of children are born after assisted reproductive technology (ART), and monitoring their long-term health effects is of interest. This study compares cancer risk in children conceived by ART to that in children conceived without.

METHODS

The Medical Birth Registry of Norway contains individual information on all children born in Norway (including information of ART conceptions). All children born between 1984 and 2011 constituted the study cohort, and cancer data were obtained from the Cancer Registry of Norway. Follow-up started at date of birth and ended on the date of the first cancer diagnosis, death, emigration, or December 31, 2011. A Cox proportional hazards model was used to calculate hazard ratios (HR) and 95% confidence intervals (CI) of overall cancer risk between children conceived by ART and those not. Cancer risk was also assessed separately for all childhood cancer types.

RESULTS

The study cohort comprised 1 628 658 children, of which 25 782 were conceived by ART. Of the total 4554 cancers, 51 occurred in ART-conceived children. Risk of overall cancer was not significantly elevated (HR 1.21; 95% CI 0.90-1.63). However, increased risk of leukemia was observed for children conceived by ART compared with those who were not (HR 1.67; 95% CI 1.02-2.73). Elevated risk of Hodgkin's lymphoma was also found for ART-conceived children (HR 3.63; 95% CI 1.12-11.72), although this was based on small numbers.

CONCLUSIONS

This population-based cohort study found elevated risks of leukemia and Hodgkin's lymphoma in children conceived by ART.

Clinical cardiovascular risk during young adulthood in offspring of hypertensive pregnancies: insights from a 20-year prospective follow-up birth cohort

OBJECTIVES

Offspring of hypertensive pregnancies have increased cardiovascular risk factors during childhood. We hypothesised that offspring of hypertensive pregnancies would demonstrate increased clinical levels of hypertension by young adult life, which would be proportional to the severity of the pregnancy complication.

DESIGN

Prospective birth cohort study

SETTING

Tertiary obstetric hospital.

PARTICIPANTS

2868 young adult offspring of women enrolled during pregnancy into the Western Australia Pregnancy Cohort (Raine) Study.

MAIN OUTCOME MEASURES

Cardiovascular risk, including incidence of hypertension and metabolic disease, in those born to hypertensive compared to normotensive pregnancies.

RESULTS

Young adult offspring of hypertensive pregnancies were 2.5 times (95% CI 1.32 to 4.56, p=0.004) more likely to have global lifetime risk (QRISK) scores above the 75th centile. Thirty per cent of 20 year olds with hypertensive blood pressures were born following a hypertensive pregnancy. Pre-eclampsia or hypertension resulting in preterm birth associated with a threefold (95% CI 1.3 to 7.0, p=0.01) greater risk of being hypertensive by age 20 years, with no differences in body mass index. Whereas pregnancy-induced hypertension associated with a smaller 3 ± 1 mm Hg blood pressure rise (p=0.001) and a twofold (95% CI 1.5 to 2.8, p=0.001) greater risk of being obese or overweight. Risk factor associations were consistent throughout early life and independent of other birth-factors.

CONCLUSIONS

Incidence of offspring hypertension was significantly increased in those whose mothers had a more complicated pregnancy history, including preterm birth and pre-eclampsia.

The EPIIC hypothesis: intrapartum effects on the neonatal epigenome and consequent health outcomes

There are many published studies about the epigenetic effects of the prenatal and infant periods on health outcomes. However, there is very little knowledge regarding the effects of the intrapartum period (labor and birth) on health and epigenetic remodeling. Although the intrapartum period is relatively short compared to the complete perinatal period, there is emerging evidence that this time frame may be a critical formative phase for the human genome. Given the debates from the National Institutes of Health and World Health Organization regarding routine childbirth procedures, it is essential to establish the state of the science concerning normal intrapartum epigenetic physiology. EPIIC (Epigenetic Impact of Childbirth) is an international, interdisciplinary research collaboration with expertise in the fields of genetics, physiology, developmental biology, epidemiology, medicine, midwifery, and nursing. We hypothesize that events during the intrapartum period - specifically the use of synthetic oxytocin, antibiotics, and cesarean section - affect the epigenetic remodeling processes and subsequent health of the mother and offspring. The rationale for this hypothesis is based on recent evidence and current best practice.

Antenatal contraception - simple, feasible, but is it safe and ethical in resource-poor environments?

In developing countries, antenatal care is used by more women than any other reproductive health services available and many women who receive antenatal care will not receive intrapartum care by a trained provider and even fewer will receive postnatal care. At present, antenatal care provides contraceptive counselling but not contraceptive provision. An important reason for this is the perceived absence of a suitable method that could be distributed or started during antenatal care. In this article, we discuss the available options. We conclude that antenatal insertion of subdermal contraceptive implants is very likely to be safe and ethically defensible where access to contraceptive services is poor.

Pre-eclampsia and offspring cardiovascular health: mechanistic insights from experimental studies

Pre-eclampsia is increasingly recognized as more than an isolated disease of pregnancy. Women who have had a pregnancy complicated by pre-eclampsia have a 4-fold increased risk of later cardiovascular disease. Intriguingly, the offspring of affected pregnancies also have an increased risk of higher blood pressure and almost double the risk of stroke in later life. Experimental approaches to identify the key features of pre-eclampsia responsible for this programming of offspring cardiovascular health, or the key biological pathways modified in the offspring, have the potential to highlight novel targets for early primary prevention strategies. As pre-eclampsia occurs in 2–5% of all pregnancies, the findings are relevant to the current healthcare of up to 3 million people in the U.K. and 15 million people in the U.S.A. In the present paper, we review the current literature that concerns potential mechanisms for adverse cardiovascular programming in offspring exposed to pre-eclampsia, considering two major areas of investigation: first, experimental models that mimic features of the in utero environment characteristic of pre-eclampsia, and secondly, how, in humans, offspring cardiovascular phenotype is altered after exposure to pre-eclampsia. We compare and contrast the findings from these two bodies of work to develop insights into the likely key pathways of relevance. The present review and analysis highlights the pivotal role of long-term changes in vascular function and identifies areas of growing interest, specifically, response to hypoxia, immune modification, epigenetics and the anti-angiogenic in utero milieu.